Understanding Modified Binders

Herman Marais introduces emerging technologies in bitumen modification including polymer modification (PMB), crumb rubber, micro filler and nanotechnologies. He concludes that PMB is the most popular modifier with exciting future prospects, crumb rubber use is expected to increase as storage stability risks are reduced and new blends are developed, micro filler shows promise, and nanotechnologies will become less expensive with increased production.

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Georges Mturi points out that about 30% of bitumen used in asphalt in South Africa is modified. In this paper he discusses the context, typical additives used, guidelines and specifications, as well as selection and classification of additives. In addition to performance, Georges explores aspects such as storage, expertise required, availability of base binders and modifier, shelf life, blending and quality control. His rule of thumb – use locally available aggregate and bitumen sources and only use additives where normal binders are limited in performance.

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Binder modification has become the norm as the performance limits of conventional bitumen have been reached. The author believes practitioners need to understand all modifiers to provide the best match for each application. This presentation provides an overview of different modifiers available and how to use them to overcome different binder limitations.

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